Impact of fiber types on gut microbiota, gut environment and gut function in fattening pigs

This study was designed to evaluate the impact of different fibrous diets on intestinal bacteria, fermentation metabolites and mucosal digestive physiology in fattening pigs. A total of 125 weaned piglets were allocated to five treatments, and each treatment was replicated in five pens of five pigs each. Pigs were fed ad libitum for 160 d. The experimental diets consisted of three-phase feeding program and four sources of fiber (maize fiber, soybean fiber, wheat bran fiber and pea fiber) were evaluated in each phase, including 10%, 20% or 30% of fiber source in the different phase feeding diets, respectively. Cereal fiber (maize fiber and wheat bran fiber) predominantly consisted of xylose and arabinose. Soybean fiber was characterized by high contents of galactose, and pea fiber was rich in glucose. Average daily feed intake (ADFI) was reduced (P < 0.05) in pigs fed SF, but supplemental pea fiber had a higher feed conversion ratio (P < 0.05) compared to control diet (CON). In ileum, increased villus height (P < 0.05) was found in pea fiber diet (PF) and wheat bran fiber diet (WB) compared to soybean fiber diet (SF). Higher ileal sucrase (P < 0.05) and maltase activities (P < 0.05) occurred in pigs fed PF compared to CON and SF. In cecum, acetate concentrations in SF (P < 0.05) and butyrate concentration in WB (P < 0.05) were higher than those in CON. Lower ileal Lactobacillus populations (P < 0.05) and higher cecal Escherichia coli populations in SF (P < 0.05) were found compared to CON. Meanwhile, cecal Lactobacillus populations in PF (P < 0.05) and Bifidobacterium populations in WB (P < 0.05) were higher than CON. The glucose transporters gene expression was up-regulated (P < 0.05) in WB and/or PF compared to CON. To be concluded, influences of dietary sources on intestinal microflora and volatile fatty acids seemed to be related to fiber components, which possibly led to the changes in intestinal mucosal digestive physiology and thus affect production parameters of fattening pigs.